1. FIELD OF THE INVENTION
This invention relates to the detection of radiation and more specifically to the detection of radiant energy in the infrared range of the electromagnetic spectrum. Still more specifically, it relates to a means and method for the detection of radiant energy wherein the position of the input energy is determined relative to fixed coordinates or points of reference.
Yet still more specifically, the invention relates to a bolometer having a thin film of metal on a heat conducting material and having contacts formed on the metal film to serve as voltage output terminals to provide the X and Y positions of incident radiant energy. Thus, if D.C. voltages are applied to the contacts in current balanced relationship, one with another, and a pencil of incident radiation is directed to the film of metal, the incident radiation changes the electrical resistance of that portion of the film receiving the radiation and the current relationship is unbalanced resulting in signals yielding voltmeter responses which are calibrated with respect to X and Y coordinates. The signals are also added to yield a measure of the radiant energy striking the detector to make the instrument insensitive to power input changes.
2. DESCRIPTION OF THE PRIOR ART
Instruments for measuring radiant energy are well known and the development of powerful lasers has generated interest in radiant energy measurement and control. Some devices use semiconductor material, and some depend on establishing a temperature gradient in a thin metal film. Various other types such as photodetectors, photovoltaic detectors and pyroelectric detectors have been used to detect radiation. We are aware of U.S. Pat. No. 3,781,748 which discloses a glass type bolometer used to detect radiation through absorption of radiation incident on the glass. The glass changes it conductivity and enables measurement of the radiation. We are also aware of the below listed United States Patents
3,487,223. This patent reveals a silicon detector wherein its inherent efficiency is improved by sandblasting the reflective surface of the apparatus.
3,813,550. This patent shows a pyroelectric detector having a crystalline body using damping to increase the frequency response.
3,851,174, DISCLOSES A DETECTOR COMPRISING A METAL FILM OF MOLYBDENUM OR TUNGSTEN AND AN INSULATING SUBSTRATE TO ESTABLISH A THERMAL GRADIENT.
3,898,605, ILLUSTRATES AN OPTICAL BOLOMETER FORMING A PORTION OF A WAVEGUIDE TO MEASURE THE RADIATION WHICH TRAVELS PARALLEL TO THE DETECTOR ELEMENT.
There are no known metallic detectors of radiant energy which operate to provide X and Y positions of the input radiation relative to fixed coordinates. The behavior of our metallic film detector yields an electrical output when calibrated against position.